<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="UTF-8">
<meta name="viewport" content="width=device-width">
<meta name="theme-color" content="#222"><meta name="generator" content="Hexo 7.3.0">

  <link rel="apple-touch-icon" sizes="180x180" href="/images/apple-touch-icon-next.png">
  <link rel="icon" type="image/png" sizes="32x32" href="/images/favicon-32x32.ico">
  <link rel="icon" type="image/png" sizes="16x16" href="/images/favicon-16x16.ico">
  <link rel="mask-icon" href="/images/logo.svg" color="#222">

<link rel="stylesheet" href="/css/main.css">



<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.1/css/all.min.css" integrity="sha256-wiz7ZSCn/btzhjKDQBms9Hx4sSeUYsDrTLg7roPstac=" crossorigin="anonymous">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.1.1/animate.min.css" integrity="sha256-PR7ttpcvz8qrF57fur/yAx1qXMFJeJFiA6pSzWi0OIE=" crossorigin="anonymous">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/fancyapps-ui/5.0.28/fancybox/fancybox.css" integrity="sha256-6cQIC71/iBIYXFK+0RHAvwmjwWzkWd+r7v/BX3/vZDc=" crossorigin="anonymous">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/pace/1.2.4/themes/green/pace-theme-minimal.css">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/pace/1.2.4/pace.min.js" integrity="sha256-gqd7YTjg/BtfqWSwsJOvndl0Bxc8gFImLEkXQT8+qj0=" crossorigin="anonymous"></script>

<script class="next-config" data-name="main" type="application/json">{"hostname":"sumumm.github.io","root":"/","images":"/images","scheme":"Gemini","darkmode":false,"version":"8.19.2","exturl":false,"sidebar":{"position":"left","display":"post","padding":18,"offset":12},"copycode":{"enable":true,"style":"mac"},"fold":{"enable":true,"height":300},"bookmark":{"enable":false,"color":"#222","save":"auto"},"mediumzoom":false,"lazyload":true,"pangu":false,"comments":{"style":"tabs","active":null,"storage":true,"lazyload":false,"nav":null},"stickytabs":false,"motion":{"enable":true,"async":true,"transition":{"menu_item":"fadeInDown","post_block":"fadeIn","post_header":"fadeInDown","post_body":"fadeInDown","coll_header":"fadeInLeft","sidebar":"fadeInUp"}},"i18n":{"placeholder":"搜索...","empty":"没有找到任何搜索结果：${query}","hits_time":"找到 ${hits} 个搜索结果（用时 ${time} 毫秒）","hits":"找到 ${hits} 个搜索结果"},"path":"/search.xml","localsearch":{"enable":true,"trigger":"auto","top_n_per_article":1,"unescape":false,"preload":false}}</script><script src="/js/config.js"></script>

    <meta name="description" content="本文主要是网络编程——网络属性的相关笔记，若笔记中有错误或者不合适的地方，欢迎批评指正😃。">
<meta property="og:type" content="article">
<meta property="og:title" content="LV06-03-网络编程-09-网络属性">
<meta property="og:url" content="https://sumumm.github.io/post/67b61f6b.html">
<meta property="og:site_name" content="苏木">
<meta property="og:description" content="本文主要是网络编程——网络属性的相关笔记，若笔记中有错误或者不合适的地方，欢迎批评指正😃。">
<meta property="og:locale" content="zh_CN">
<meta property="og:image" content="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV06-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B/LV06-03-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B-09-%E7%BD%91%E7%BB%9C%E5%B1%9E%E6%80%A7/img/image-20220705141116835.png">
<meta property="article:published_time" content="2024-10-27T03:50:04.000Z">
<meta property="article:modified_time" content="2025-06-13T16:25:56.999Z">
<meta property="article:author" content="苏木">
<meta property="article:tag" content="LV06-网络编程">
<meta name="twitter:card" content="summary">
<meta name="twitter:image" content="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV06-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B/LV06-03-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B-09-%E7%BD%91%E7%BB%9C%E5%B1%9E%E6%80%A7/img/image-20220705141116835.png">


<link rel="canonical" href="https://sumumm.github.io/post/67b61f6b.html">



<script class="next-config" data-name="page" type="application/json">{"sidebar":"","isHome":false,"isPost":true,"lang":"zh-CN","comments":"","permalink":"https://sumumm.github.io/post/67b61f6b.html","path":"post/67b61f6b.html","title":"LV06-03-网络编程-09-网络属性"}</script>

<script class="next-config" data-name="calendar" type="application/json">""</script>
<title>LV06-03-网络编程-09-网络属性 | 苏木</title>
  








    <script src="/js/browser_tools_disable.js"></script>

  <noscript>
    <link rel="stylesheet" href="/css/noscript.css">
  </noscript>
<!-- hexo injector head_end start --><link rel="stylesheet" href="https://unpkg.com/hexo-next-tags-plus@latest/lib/tag_plus.css" media="defer" onload="this.media='all'"><!-- hexo injector head_end end --></head>

<body itemscope itemtype="http://schema.org/WebPage" class="use-motion">
  <div class="headband"></div>

  <main class="main">
    <div class="column">
      <header class="header" itemscope itemtype="http://schema.org/WPHeader"><div class="site-brand-container">
  <div class="site-nav-toggle">
    <div class="toggle" aria-label="切换导航栏" role="button">
        <span class="toggle-line"></span>
        <span class="toggle-line"></span>
        <span class="toggle-line"></span>
    </div>
  </div>

  <div class="site-meta">

    <a href="/" class="brand" rel="start">
      <i class="logo-line"></i>
      <p class="site-title">苏木</p>
      <i class="logo-line"></i>
    </a>
      <p class="site-subtitle" itemprop="description">我的学习之路</p>
  </div>

  <div class="site-nav-right">
    <div class="toggle popup-trigger" aria-label="搜索" role="button">
        <i class="fa fa-search fa-fw fa-lg"></i>
    </div>
  </div>
</div>



<nav class="site-nav">
  <ul class="main-menu menu"><li class="menu-item menu-item-home"><a href="/" rel="section"><i class="fa fa-home fa-fw"></i>苏木的家</a></li><li class="menu-item menu-item-categories"><a href="/categories/" rel="section"><i class="fa fa-th fa-fw"></i>分类页<span class="badge">42</span></a></li><li class="menu-item menu-item-archives"><a href="/archives/" rel="section"><i class="fa fa-archive fa-fw"></i>归档页<span class="badge">673</span></a></li><li class="menu-item menu-item-flink"><a href="/flink/" rel="section"><i class="fa fa-link fa-fw"></i>友人帐</a></li><li class="menu-item menu-item-about"><a href="/about/" rel="section"><i class="fa fa-user fa-fw"></i>关于我</a></li>
      <li class="menu-item menu-item-search">
        <a role="button" class="popup-trigger"><i class="fa fa-search fa-fw"></i>搜索
        </a>
      </li>
  </ul>
</nav>



  <div class="search-pop-overlay">
    <div class="popup search-popup"><div class="search-header">
  <span class="search-icon">
    <i class="fa fa-search"></i>
  </span>
  <div class="search-input-container">
    <input autocomplete="off" autocapitalize="off" maxlength="80"
           placeholder="搜索..." spellcheck="false"
           type="search" class="search-input">
  </div>
  <span class="popup-btn-close" role="button">
    <i class="fa fa-times-circle"></i>
  </span>
</div>
<div class="search-result-container no-result">
  <div class="search-result-icon">
    <i class="fa fa-spinner fa-pulse fa-5x"></i>
  </div>
</div>

    </div>
  </div>

</header>
        
  
  <aside class="sidebar">

    <div class="sidebar-inner sidebar-nav-active sidebar-toc-active">
      <ul class="sidebar-nav">
        <li class="sidebar-nav-toc">
          文章目录
        </li>
        <li class="sidebar-nav-overview">
          站点概览
        </li>
      </ul>

      <div class="sidebar-panel-container">
        <!--noindex-->
        <div class="post-toc-wrap sidebar-panel">
            <div class="post-toc animated"><ol class="nav"><li class="nav-item nav-level-1"><a class="nav-link" href="#%E4%B8%80%E3%80%81%E7%BD%91%E7%BB%9C%E5%B1%9E%E6%80%A7"><span class="nav-text">一、网络属性</span></a><ol class="nav-child"><li class="nav-item nav-level-2"><a class="nav-link" href="#1-getsockopt-%E5%87%BD%E6%95%B0"><span class="nav-text">1. getsockopt()函数</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-%E5%87%BD%E6%95%B0%E8%AF%B4%E6%98%8E"><span class="nav-text">1.1 函数说明</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-%E4%BD%BF%E7%94%A8%E5%AE%9E%E4%BE%8B"><span class="nav-text">1.2 使用实例</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#2-setsockopt-%E5%87%BD%E6%95%B0"><span class="nav-text">2. setsockopt()函数</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#2-1-%E5%87%BD%E6%95%B0%E8%AF%B4%E6%98%8E"><span class="nav-text">2.1 函数说明</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#2-2-%E4%BD%BF%E7%94%A8%E5%AE%9E%E4%BE%8B"><span class="nav-text">2.2 使用实例</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#3-getsockname-%E5%87%BD%E6%95%B0"><span class="nav-text">3. getsockname()函数</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#3-1-%E5%87%BD%E6%95%B0%E8%AF%B4%E6%98%8E"><span class="nav-text">3.1 函数说明</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#3-2-%E4%BD%BF%E7%94%A8%E5%AE%9E%E4%BE%8B"><span class="nav-text">3.2 使用实例</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#4-getpeername-%E5%87%BD%E6%95%B0"><span class="nav-text">4. getpeername()函数</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#4-1-%E5%87%BD%E6%95%B0%E8%AF%B4%E6%98%8E"><span class="nav-text">4.1 函数说明</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#4-2-%E4%BD%BF%E7%94%A8%E5%AE%9E%E4%BE%8B"><span class="nav-text">4.2 使用实例</span></a></li></ol></li></ol></li><li class="nav-item nav-level-1"><a class="nav-link" href="#%E4%BA%8C%E3%80%81%E7%BD%91%E7%BB%9C%E8%B6%85%E6%97%B6%E6%A3%80%E6%B5%8B"><span class="nav-text">二、网络超时检测</span></a><ol class="nav-child"><li class="nav-item nav-level-2"><a class="nav-link" href="#1-%E4%B8%BA%E4%BB%80%E4%B9%88%E8%A6%81%E8%B6%85%E6%97%B6%E6%A3%80%E6%B5%8B%EF%BC%9F"><span class="nav-text">1. 为什么要超时检测？</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#2-socket%E5%B1%9E%E6%80%A7%E8%AE%BE%E7%BD%AE%E8%B6%85%E6%97%B6"><span class="nav-text">2. socket属性设置超时</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#2-1-%E9%80%89%E9%A1%B9%E4%B8%8E%E7%BB%93%E6%9E%84%E4%BD%93"><span class="nav-text">2.1 选项与结构体</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#2-2-%E4%BD%BF%E7%94%A8%E5%AE%9E%E4%BE%8B-1"><span class="nav-text">2.2 使用实例</span></a><ol class="nav-child"><li class="nav-item nav-level-4"><a class="nav-link" href="#2-2-1-server%E6%9C%8D%E5%8A%A1%E5%99%A8%E7%AB%AF"><span class="nav-text">2.2.1 server服务器端</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#2-2-2-client%E5%AE%A2%E6%88%B7%E7%AB%AF"><span class="nav-text">2.2.2 client客户端</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#2-2-3-Makefile"><span class="nav-text">2.2.3 Makefile</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#2-2-4-%E6%B5%8B%E8%AF%95%E7%BB%93%E6%9E%9C"><span class="nav-text">2.2.4 测试结果</span></a></li></ol></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#3-%E4%BD%BF%E7%94%A8%E5%87%BD%E6%95%B0%E8%87%AA%E8%BA%AB%E5%8F%82%E6%95%B0"><span class="nav-text">3. 使用函数自身参数</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#4-%E5%AE%9A%E6%97%B6%E5%99%A8%E4%B8%AD%E6%8E%A5%E6%94%B6"><span class="nav-text">4. 定时器中接收</span></a></li></ol></li><li class="nav-item nav-level-1"><a class="nav-link" href="#%E4%B8%89%E3%80%81TCP%E5%AE%A2%E6%88%B7%E7%AB%AF%E6%8E%89%E7%BA%BF%E4%BA%86%EF%BC%9F"><span class="nav-text">三、TCP客户端掉线了？</span></a><ol class="nav-child"><li class="nav-item nav-level-2"><a class="nav-link" href="#1-%E5%AE%A2%E6%88%B7%E7%AB%AF%E5%BC%82%E5%B8%B8%E6%8E%89%E7%BA%BF%E7%9A%84%E5%88%A4%E6%96%AD"><span class="nav-text">1. 客户端异常掉线的判断</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-%E5%BA%94%E7%94%A8%E5%B1%82%E8%87%AA%E5%AE%9A%E4%B9%89%E5%BF%83%E8%B7%B3%E5%8C%85%E7%A8%8B%E5%BA%8F"><span class="nav-text">1.1 应用层自定义心跳包程序</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-TCP%E4%B8%AD%E4%BD%BF%E7%94%A8SO-KEEPALIVE%E5%A5%97%E6%8E%A5%E5%AD%97%E9%80%89%E9%A1%B9"><span class="nav-text">1.2 TCP中使用SO_KEEPALIVE套接字选项</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-3-%E5%86%85%E6%A0%B8%E6%A3%80%E6%B5%8B"><span class="nav-text">1.3 内核检测</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#2-SO-KEEPALIVE%E7%9A%84%E4%BD%BF%E7%94%A8"><span class="nav-text">2. SO_KEEPALIVE的使用</span></a></li></ol></li></ol></div>
        </div>
        <!--/noindex-->

        <div class="site-overview-wrap sidebar-panel">
          <div class="site-author animated" itemprop="author" itemscope itemtype="http://schema.org/Person">
    <img class="site-author-image" itemprop="image" alt="苏木"
      src="/images/avatar.jpg">
  <p class="site-author-name" itemprop="name">苏木</p>
  <div class="site-description" itemprop="description">莫道桑榆晚，为霞尚满天</div>
</div>
<div class="site-state-wrap animated">
  <nav class="site-state">
      <div class="site-state-item site-state-posts">
        <a href="/archives/">
          <span class="site-state-item-count">673</span>
          <span class="site-state-item-name">日志</span>
        </a>
      </div>
      <div class="site-state-item site-state-categories">
          <a href="/categories/">
        <span class="site-state-item-count">42</span>
        <span class="site-state-item-name">分类</span></a>
      </div>
      <div class="site-state-item site-state-tags">
        <span class="site-state-item-count">43</span>
        <span class="site-state-item-name">标签</span>
      </div>
  </nav>
</div>
  <div class="links-of-author animated">
      <span class="links-of-author-item">
        <a href="https://github.com/sumumm" title="GitHub → https:&#x2F;&#x2F;github.com&#x2F;sumumm" rel="noopener me" target="_blank"><i class="fab fa-github fa-fw"></i>GitHub</a>
      </span>
  </div>

        </div>
      </div>
    </div>

    
  </aside>


    </div>

    <div class="main-inner post posts-expand">


  


<div class="post-block">
  
  

  <article itemscope itemtype="http://schema.org/Article" class="post-content" lang="zh-CN">
    <link itemprop="mainEntityOfPage" href="https://sumumm.github.io/post/67b61f6b.html">

    <span hidden itemprop="author" itemscope itemtype="http://schema.org/Person">
      <meta itemprop="image" content="/images/avatar.jpg">
      <meta itemprop="name" content="苏木">
    </span>

    <span hidden itemprop="publisher" itemscope itemtype="http://schema.org/Organization">
      <meta itemprop="name" content="苏木">
      <meta itemprop="description" content="莫道桑榆晚，为霞尚满天">
    </span>

    <span hidden itemprop="post" itemscope itemtype="http://schema.org/CreativeWork">
      <meta itemprop="name" content="LV06-03-网络编程-09-网络属性 | 苏木">
      <meta itemprop="description" content="">
    </span>
      <header class="post-header">
        <h1 class="post-title" itemprop="name headline">
          LV06-03-网络编程-09-网络属性
        </h1>

        <div class="post-meta-container">
          <div class="post-meta">
    <span class="post-meta-item">
      <span class="post-meta-item-icon">
        <i class="far fa-calendar"></i>
      </span>
      <span class="post-meta-item-text">发表于</span>

      <time title="创建时间：2024-10-27 11:50:04" itemprop="dateCreated datePublished" datetime="2024-10-27T11:50:04+08:00">2024-10-27</time>
    </span>
    <span class="post-meta-item">
      <span class="post-meta-item-icon">
        <i class="far fa-folder"></i>
      </span>
      <span class="post-meta-item-text">分类于</span>
        <span itemprop="about" itemscope itemtype="http://schema.org/Thing">
          <a href="/categories/%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/" itemprop="url" rel="index"><span itemprop="name">嵌入式开发</span></a>
        </span>
          ，
        <span itemprop="about" itemscope itemtype="http://schema.org/Thing">
          <a href="/categories/%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/" itemprop="url" rel="index"><span itemprop="name">01HQ课程体系</span></a>
        </span>
          ，
        <span itemprop="about" itemscope itemtype="http://schema.org/Thing">
          <a href="/categories/%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV06-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B/" itemprop="url" rel="index"><span itemprop="name">LV06-网络编程</span></a>
        </span>
    </span>

  
    <span class="post-meta-break"></span>
    <span class="post-meta-item" title="本文字数">
      <span class="post-meta-item-icon">
        <i class="far fa-file-word"></i>
      </span>
      <span class="post-meta-item-text">本文字数：</span>
      <span>7.3k</span>
    </span>
    <span class="post-meta-item" title="阅读时长">
      <span class="post-meta-item-icon">
        <i class="far fa-clock"></i>
      </span>
      <span class="post-meta-item-text">阅读时长 &asymp;</span>
      <span>27 分钟</span>
    </span>
</div>

        </div>
      </header>

    
    
    
    <div class="post-body" itemprop="articleBody"><p>本文主要是网络编程——网络属性的相关笔记，若笔记中有错误或者不合适的地方，欢迎批评指正😃。</p>
<span id="more"></span>

<!-- Photo: https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV06-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B/LV06-03-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B-09-%E7%BD%91%E7%BB%9C%E5%B1%9E%E6%80%A7/img/ -->

<details class="folding-tag" blue><summary> 点击查看使用工具及版本 </summary>
              <div class='content'>
              <table>    <tr>        <td align="center" width=150px>Windows</td>        <td align="left">windows11</td>    </tr>    <tr>        <td align="center">Ubuntu</td>        <td align="left">Ubuntu16.04的64位版本</td>      </tr>    <tr>        <td align="center">VMware® Workstation 16 Pro</td>        <td align="left">16.2.3 build-19376536</td>      </tr>    <tr>        <td align="center">SecureCRT</td>        <td align="left">Version 8.7.2 (x64 build 2214)   -   正式版-2020年5月14日</td>      </tr>    <tr>        <td align="center">开发板</td>        <td align="left">正点原子 i.MX6ULL Linux阿尔法开发板</td>      </tr>    <tr>        <td align="center">uboot</td>        <td align="left">NXP官方提供的uboot，NXP提供的版本为uboot-imx-rel_imx_4.1.15_2.1.0_ga(使用的uboot版本为U-Boot 2016.03)</td>      </tr>    <tr>        <td align="center">linux内核</td>        <td align="left">linux-4.15(NXP官方提供)</td>      </tr>    <tr>        <td align="center">STM32开发板</td>        <td align="left">正点原子战舰V3(STM32F103ZET6)</td>      </tr></table>
              </div>
            </details>

<details class="folding-tag" blue><summary> 点击查看本文参考资料 </summary>
              <div class='content'>
              <table>    <tr><td align="center">参考方向  </td><td align="center">参考原文</td></tr>    <tr><td align="center">---</td><td align="left"><a href="" target="_blank">--- <i class="fa fa-external-link-alt"></i> </a></td></tr></table> 
              </div>
            </details>

<details class="folding-tag" blue><summary> 点击查看相关文件下载 </summary>
              <div class='content'>
              <table>    <tr>        <td align="center">---</td>        <td align="left">--- <a href="" target="_blank">  <i class="fa fa-external-link-alt"></i></a></td>      </tr></table>
              </div>
            </details>

<h1 id="一、网络属性"><a href="#一、网络属性" class="headerlink" title="一、网络属性"></a><font size=3>一、网络属性</font></h1><p>记得前边我们使用过<code>setsockopt</code>函数设置过允许地址重用，终于到了详细学习该函数的部分了。</p>
<h2 id="1-getsockopt-函数"><a href="#1-getsockopt-函数" class="headerlink" title="1. getsockopt()函数"></a><font size=3>1. <code>getsockopt()</code>函数</font></h2><h3 id="1-1-函数说明"><a href="#1-1-函数说明" class="headerlink" title="1.1 函数说明"></a><font size=3>1.1 函数说明</font></h3><p>在<code>linux</code>下可以使用<code>man 2 getsockopt</code>命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span>          <span class="comment">/* See NOTES */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> </span></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">getsockopt</span><span class="params">(<span class="type">int</span> sockfd, <span class="type">int</span> level, <span class="type">int</span> optname, <span class="type">void</span> *optval, <span class="type">socklen_t</span> *optlen)</span>;</span><br><span class="line"></span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数可以<strong>获取</strong>某个<code>socket</code>套接字的属性选项。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li><code>sockfd</code>：<code>int</code>类型，表示需要获取选项的套接字。</li>
<li><code>level</code>：<code>int</code>类型，选项所在的协议层。</li>
</ul>
<details class="folding-tag" blue><summary> 点击查看 level 可取的值 </summary>
              <div class='content'>
              <table>    <tr><td align="left" width=150px>SOL_SOCKET</td><td align="left">通用套接字选项</td></tr>    <tr><td align="left" width=150px>IPPROTO_IP</td><td align="left">IP选项</td></tr>    <tr><td align="left" width=150px>IPPROTO_TCP</td><td align="left">TCP选项</td></tr></table>
              </div>
            </details>

<ul>
<li><code>optname</code>：<code>int</code>类型，表示要获取的选项名称。</li>
</ul>
<details class="folding-tag" blue><summary> 点击查看 optname 常用可取的值 </summary>
              <div class='content'>
              <p>我们可以使用如下命令查看这些选项：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">man 7 socket # 打开手册后查看 Socket options 部分</span><br><span class="line">man 7 ip     # 打开手册后查看 Socket options 部分</span><br><span class="line">man 7 ipv6   # 打开手册后查看 Socket options 部分</span><br><span class="line">man 7 tcp    # 打开手册后查看 Socket options 部分</span><br></pre></td></tr></table></figure><p>常用选项如下：</p><table>    <tr><td align="center">选项名称</td><td align="center">说明</td><td align="center">数据类型</td></tr>    <tr><td align="center" colspan="3" style="color:red;">SOL_SOCKET</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_BROADCAST</td><td align="left" style="font-weight: bold;">允许发送广播数据</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left">SO_DEBUG</td><td align="left">允许调试</td><td align="left">int</td></tr>    <tr><td align="left">SO_DONTROUTE</td><td align="left">不查找路由</td><td align="left">int</td></tr>    <tr><td align="left">SO_ERROR</td><td align="left">获得套接字错误</td><td align="left">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_KEEPALIVE</td><td align="left">保持连接</td><td align="left">int</td></tr>    <tr><td align="left">SO_LINGER</td><td align="left">延迟关闭连接</td><td align="left">struct linger</td></tr>    <tr><td align="left">SO_OOBINLINE</td><td align="left">带外数据放入正常数据流　</td><td align="left">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_RCVBUF</td><td align="left" style="font-weight: bold;">接收缓冲区大小</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_SNDBUF</td><td align="left" style="font-weight: bold;">发送缓冲区大小</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_RCVLOWAT</td><td align="left" style="font-weight: bold;">接收缓冲区下限</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_SNDLOWAT</td><td align="left" style="font-weight: bold;">发送缓冲区下限</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_RCVTIMEO</td><td align="left" style="font-weight: bold;">接收超时</td><td align="left" style="font-weight: bold;">struct timeval</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_SNDTIMEO</td><td align="left" style="font-weight: bold;">发送超时</td><td align="left" style="font-weight: bold;">struct timeval</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_REUSEADDR </td><td align="left" style="font-weight: bold;">允许重用本地地址和端口　</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left">SO_TYPE</td><td align="left">获得套接字类型</td><td align="left">int</td></tr>    <tr><td align="left">SO_BSDCOMPAT</td><td align="left">与BSD系统兼容</td><td align="left">int</td></tr>    <tr><td align="center" colspan="3" style="color:red;">IPPROTO_IP</td></tr>    <tr><td align="left">IP_HDRINCL</td><td align="left">在数据包中包含IP首部</td><td align="left">int</td></tr>    <tr><td align="left">IP_OPTINOS</td><td align="left">IP首部选项</td><td align="left">int</td></tr>    <tr><td align="left">IP_TOS</td><td align="left">服务类型</td><td align="left"></td></tr>    <tr><td align="left">IP_TTL</td><td align="left">生存时间</td><td align="left">int</td></tr>    <tr><td align="center" colspan="3" style="color:red;">IPPRO_TCP</td></tr>    <tr><td align="left">TCP_MAXSEG</td><td align="left">TCP最大数据段的大小</td><td align="left">int</td></tr>    <tr><td align="left">TCP_NODELAY</td><td align="left">不使用Nagle算法</td><td align="left">int</td></tr></table>
              </div>
            </details>

<ul>
<li><code>optval</code>：<code>void</code>类型指针变量，获取的套接字选项，需要根据选项名称的数据类型进行强制类型转换。</li>
<li><code>optlen</code>：<code>socklen_t </code>类型指针变量，表示<code>optval</code>的长度，要注意需要传入的是一个地址。</li>
</ul>
<p><strong>【返回值】</strong><code>int</code>类型，成功返回<code>0</code>，失败返回<code>-1</code>，并设置<code>errno</code>表示错误类型。</p>
<p><strong>【使用格式】</strong>一般使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span>          <span class="comment">/* See NOTES */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> </span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"><span class="type">int</span> sendBuff;</span><br><span class="line"><span class="type">socklen_t</span> optLen = <span class="keyword">sizeof</span>(<span class="type">int</span>);</span><br><span class="line"><span class="type">int</span> socket_fd = socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>);</span><br><span class="line">getsockopt(socket_fd, SOL_SOCKET, SO_SNDBUF, (<span class="type">int</span> *)&amp;sendBuff, &amp;optLen);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong><code>none</code></p>
<h3 id="1-2-使用实例"><a href="#1-2-使用实例" class="headerlink" title="1.2 使用实例"></a><font size=3>1.2 使用实例</font></h3><details class="folding-tag" blue><summary> 点击查看实例 </summary>
              <div class='content'>
              <figure class="highlight c"><figcaption><span>test.c</span></figcaption><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span>          <span class="comment">/* See NOTES */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc, <span class="type">char</span> *argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="type">int</span> sendBuff;</span><br><span class="line">	<span class="type">socklen_t</span> optLen = <span class="keyword">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">	<span class="type">int</span> socket_fd = socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>);</span><br><span class="line">	getsockopt(socket_fd, SOL_SOCKET, SO_SNDBUF, (<span class="type">int</span> *)&amp;sendBuff, &amp;optLen);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;sendBuff length: %dKB\n&quot;</span>, sendBuff / <span class="number">1024</span>);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><p>在终端执行以下命令编译程序：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">gcc test.c -Wall # 生成可执行文件 a.out </span><br><span class="line">./a.out # 执行可执行程序</span><br></pre></td></tr></table></figure><p>然后，终端会有以下信息显示：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sendBuff length: 16KB</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<h2 id="2-setsockopt-函数"><a href="#2-setsockopt-函数" class="headerlink" title="2. setsockopt()函数"></a><font size=3>2. <code>setsockopt()</code>函数</font></h2><h3 id="2-1-函数说明"><a href="#2-1-函数说明" class="headerlink" title="2.1 函数说明"></a><font size=3>2.1 函数说明</font></h3><p>在<code>linux</code>下可以使用<code>man 2 setsockopt</code>命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span>          <span class="comment">/* See NOTES */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> </span></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">setsockopt</span><span class="params">(<span class="type">int</span> sockfd, <span class="type">int</span> level, <span class="type">int</span> optname, <span class="type">const</span> <span class="type">void</span> *optval, <span class="type">socklen_t</span> optlen)</span>;</span><br><span class="line"></span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数可以<strong>设置</strong>某个<code>socket</code>套接字的属性选项。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li><code>sockfd</code>：<code>int</code>类型，表示需要设置选项的套接字。</li>
<li><code>level</code>：<code>int</code>类型，选项所在的协议层。</li>
</ul>
<details class="folding-tag" blue><summary> 点击查看 level 可取的值 </summary>
              <div class='content'>
              <table>    <tr><td align="left" width=150px>SOL_SOCKET</td><td align="left">通用套接字选项</td></tr>    <tr><td align="left" width=150px>IPPROTO_IP</td><td align="left">IP选项</td></tr>    <tr><td align="left" width=150px>IPPROTO_TCP</td><td align="left">TCP选项</td></tr></table>
              </div>
            </details>

<ul>
<li><code>optname</code>：<code>int</code>类型，表示要设置的选项名称。</li>
</ul>
<details class="folding-tag" blue><summary> 点击查看 optname 常用可取的值 </summary>
              <div class='content'>
              <p>我们可以使用如下命令查看这些选项：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">man 7 socket # 打开手册后查看 Socket options 部分</span><br><span class="line">man 7 ip     # 打开手册后查看 Socket options 部分</span><br><span class="line">man 7 ipv6   # 打开手册后查看 Socket options 部分</span><br><span class="line">man 7 tcp    # 打开手册后查看 Socket options 部分</span><br></pre></td></tr></table></figure><p>常用选项如下：</p><table>    <tr><td align="center">选项名称</td><td align="center">说明</td><td align="center">数据类型</td></tr>    <tr><td align="center" colspan="3" style="color:red;">SOL_SOCKET</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_BROADCAST</td><td align="left" style="font-weight: bold;">允许发送广播数据</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left">SO_DEBUG</td><td align="left">允许调试</td><td align="left">int</td></tr>    <tr><td align="left">SO_DONTROUTE</td><td align="left">不查找路由</td><td align="left">int</td></tr>    <tr><td align="left">SO_ERROR</td><td align="left">获得套接字错误</td><td align="left">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_KEEPALIVE</td><td align="left">保持连接</td><td align="left">int</td></tr>    <tr><td align="left">SO_LINGER</td><td align="left">延迟关闭连接</td><td align="left">struct linger</td></tr>    <tr><td align="left">SO_OOBINLINE</td><td align="left">带外数据放入正常数据流　</td><td align="left">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_RCVBUF</td><td align="left" style="font-weight: bold;">接收缓冲区大小</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_SNDBUF</td><td align="left" style="font-weight: bold;">发送缓冲区大小</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_RCVLOWAT</td><td align="left" style="font-weight: bold;">接收缓冲区下限</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_SNDLOWAT</td><td align="left" style="font-weight: bold;">发送缓冲区下限</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_RCVTIMEO</td><td align="left" style="font-weight: bold;">接收超时</td><td align="left" style="font-weight: bold;">struct timeval</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_SNDTIMEO</td><td align="left" style="font-weight: bold;">发送超时</td><td align="left" style="font-weight: bold;">struct timeval</td></tr>    <tr><td align="left" style="font-weight: bold;">SO_REUSEADDR </td><td align="left" style="font-weight: bold;">允许重用本地地址和端口　</td><td align="left" style="font-weight: bold;">int</td></tr>    <tr><td align="left">SO_TYPE</td><td align="left">获得套接字类型</td><td align="left">int</td></tr>    <tr><td align="left">SO_BSDCOMPAT</td><td align="left">与BSD系统兼容</td><td align="left">int</td></tr>    <tr><td align="center" colspan="3" style="color:red;">IPPROTO_IP</td></tr>    <tr><td align="left">IP_HDRINCL</td><td align="left">在数据包中包含IP首部</td><td align="left">int</td></tr>    <tr><td align="left">IP_OPTINOS</td><td align="left">IP首部选项</td><td align="left">int</td></tr>    <tr><td align="left">IP_TOS</td><td align="left">服务类型</td><td align="left"></td></tr>    <tr><td align="left">IP_TTL</td><td align="left">生存时间</td><td align="left">int</td></tr>    <tr><td align="center" colspan="3" style="color:red;">IPPRO_TCP</td></tr>    <tr><td align="left">TCP_MAXSEG</td><td align="left">TCP最大数据段的大小</td><td align="left">int</td></tr>    <tr><td align="left">TCP_NODELAY</td><td align="left">不使用Nagle算法</td><td align="left">int</td></tr></table>
              </div>
            </details>

<ul>
<li><code>optval</code>：<code>void</code>类型指针变量，设置的套接字选项，需要根据选项名称的数据类型进行强制类型转换。</li>
<li><code>optlen</code>：<code>socklen_t </code>类型，表示<code>optval</code>的长度，要注意需要传入的是一个变量。</li>
</ul>
<p><strong>【返回值】</strong><code>int</code>类型，成功返回<code>0</code>，失败返回<code>-1</code>，并设置<code>errno</code>表示错误类型。</p>
<p><strong>【使用格式】</strong>一般使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span>          <span class="comment">/* See NOTES */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> </span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"><span class="type">int</span> socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>);</span><br><span class="line"><span class="type">int</span> b_reuse = <span class="number">1</span>;</span><br><span class="line">setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &amp;b_reuse, <span class="keyword">sizeof</span> (<span class="type">int</span>));</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong><code>none</code></p>
<h3 id="2-2-使用实例"><a href="#2-2-使用实例" class="headerlink" title="2.2 使用实例"></a><font size=3>2.2 使用实例</font></h3><details class="folding-tag" blue><summary> 点击查看实例 </summary>
              <div class='content'>
              <figure class="highlight c"><figcaption><span>test.c</span></figcaption><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span>          <span class="comment">/* See NOTES */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> </span></span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc, <span class="type">char</span> *argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="type">int</span> b_reuse;</span><br><span class="line">	<span class="type">socklen_t</span> optLen = <span class="keyword">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">	<span class="type">int</span> socket_fd = socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>);</span><br><span class="line">	getsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, (<span class="type">int</span> *)&amp;b_reuse, &amp;optLen);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;b_reuse: %d\n&quot;</span>, b_reuse);</span><br><span class="line">	<span class="type">int</span> a_reuse = <span class="number">1</span>;</span><br><span class="line">	setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &amp;a_reuse, <span class="keyword">sizeof</span> (<span class="type">int</span>));</span><br><span class="line">	getsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, (<span class="type">int</span> *)&amp;b_reuse, &amp;optLen);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;b_reuse: %d\n&quot;</span>, b_reuse);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><p>在终端执行以下命令编译程序：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">gcc test.c -Wall # 生成可执行文件 a.out </span><br><span class="line">./a.out # 执行可执行程序</span><br></pre></td></tr></table></figure><p>然后，终端会有以下信息显示：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">b_reuse: 0</span><br><span class="line">b_reuse: 1</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<h2 id="3-getsockname-函数"><a href="#3-getsockname-函数" class="headerlink" title="3. getsockname()函数"></a><font size=3>3. <code>getsockname()</code>函数</font></h2><h3 id="3-1-函数说明"><a href="#3-1-函数说明" class="headerlink" title="3.1 函数说明"></a><font size=3>3.1 函数说明</font></h3><p>在<code>linux</code>下可以使用<code>man 2 getsockname</code>命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">getsockname</span><span class="params">(<span class="type">int</span> sockfd, <span class="keyword">struct</span> sockaddr *addr, <span class="type">socklen_t</span> *addrlen)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数可以用于获取与某个套接字关联的<strong>本地协议地址</strong>。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li><p><code>sockfd</code>：<code>int</code>类型，表示已经创建的<code>socket</code>套接字。</p>
</li>
<li><p><code>addr</code>：<code>struct sockaddr</code>类型的结构体指针变量，指向一个<code>struct sockaddr</code>类型变量，该结构体中含有要绑定的<code>IP</code>地址及端口号。但是呢，我们一般不使用这个类型，一般会使用<code>struct sockaddr_in</code>类型，具体原因后边前边介绍<code>bind</code>函数的时候已经说过了。</p>
</li>
<li><p><code>addrlen</code>：<code>socklen_t</code>类型指针变量，用于指定<code>addr</code>所指向的结构体对应的字节长度。</p>
</li>
</ul>
<p><strong>【返回值】</strong><code>int</code>类型，成功返回<code>0</code>，失败返回<code>-1</code>，并设置<code>errno</code>表示错误类型。</p>
<p><strong>【使用格式】</strong>一般使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span>      <span class="comment">/* perror scanf printf */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> <span class="comment">/* socket inet_addr bind listen accept send */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;arpa/inet.h&gt;</span>  <span class="comment">/* htons  inet_addr inet_pton */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;netinet/in.h&gt;</span> <span class="comment">/* ntohs  inet_addr inet_ntop*/</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"></span><br><span class="line"><span class="type">char</span> ipv4_addr[<span class="number">16</span>] = &#123;&#125;;</span><br><span class="line"><span class="type">int</span> port = <span class="number">-1</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>);</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">sockaddr_in</span> <span class="title">sin</span>;</span></span><br><span class="line"><span class="type">socklen_t</span> addrlen = <span class="keyword">sizeof</span>(<span class="built_in">sin</span>);</span><br><span class="line"></span><br><span class="line"><span class="keyword">if</span>( getsockname(scoket_fd, (<span class="keyword">struct</span> sockaddr *)&amp;<span class="built_in">sin</span>, &amp;addrlen) &lt; <span class="number">0</span> )</span><br><span class="line">&#123;</span><br><span class="line">	perror(<span class="string">&quot;[error]getsockname&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">/* 获取本地IP */</span></span><br><span class="line"><span class="keyword">if</span> (!inet_ntop(AF_INET, (<span class="type">void</span> *)&amp;<span class="built_in">sin</span>.sin_addr, ipv4_addr, <span class="keyword">sizeof</span>(<span class="built_in">sin</span>)))</span><br><span class="line">&#123;</span><br><span class="line">	perror(<span class="string">&quot;[error]inet_ntop&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">/* 获取本地端口 */</span></span><br><span class="line">port = ntohs(<span class="built_in">sin</span>.sin_port);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong><code>none</code></p>
<h3 id="3-2-使用实例"><a href="#3-2-使用实例" class="headerlink" title="3.2 使用实例"></a><font size=3>3.2 使用实例</font></h3><p>暂无</p>
<h2 id="4-getpeername-函数"><a href="#4-getpeername-函数" class="headerlink" title="4. getpeername()函数"></a><font size=3>4. <code>getpeername()</code>函数</font></h2><h3 id="4-1-函数说明"><a href="#4-1-函数说明" class="headerlink" title="4.1 函数说明"></a><font size=3>4.1 函数说明</font></h3><p>在<code>linux</code>下可以使用<code>man 2 getpeername</code>命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span>  <span class="title function_">getpeername</span><span class="params">(<span class="type">int</span> sockfd, <span class="keyword">struct</span> sockaddr *addr, <span class="type">socklen_t</span> *addrlen)</span>;</span><br><span class="line"></span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数可以用于获取与某个套接字关联的<strong>对端协议地址</strong>（如果在服务器端调用的话，可以获取客户端的<code>IP</code>和端口，与<code>accept()</code>函数传出的信息相同）。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li><p><code>sockfd</code>：<code>int</code>类型，表示已经创建的<code>socket</code>套接字。</p>
</li>
<li><p><code>addr</code>：<code>struct sockaddr</code>类型的结构体指针变量，指向一个<code>struct sockaddr</code>类型变量，该结构体中含有要绑定的<code>IP</code>地址及端口号。但是呢，我们一般不使用这个类型，一般会使用<code>struct sockaddr_in</code>类型，具体原因后边前边介绍<code>bind</code>函数的时候已经说过了。</p>
</li>
<li><p><code>addrlen</code>：<code>socklen_t</code>类型指针变量，用于指定<code>addr</code>所指向的结构体对应的字节长度。</p>
</li>
</ul>
<p><strong>【返回值】</strong><code>int</code>类型，成功返回<code>0</code>，失败返回<code>-1</code>，并设置<code>errno</code>表示错误类型。</p>
<p><strong>【使用格式】</strong>一般使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span>      <span class="comment">/* perror scanf printf */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> <span class="comment">/* socket inet_addr bind listen accept send */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;arpa/inet.h&gt;</span>  <span class="comment">/* htons  inet_addr inet_pton */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;netinet/in.h&gt;</span> <span class="comment">/* ntohs  inet_addr inet_ntop*/</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"><span class="type">char</span> ipv4_addr[<span class="number">16</span>] = &#123;&#125;;</span><br><span class="line"><span class="type">int</span> port = <span class="number">-1</span>;</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">sockaddr_in</span> <span class="title">cin</span>;</span>          <span class="comment">/* 用于存储成功连接的客户端的IP信息 */</span></span><br><span class="line"><span class="type">socklen_t</span> addrlen = <span class="keyword">sizeof</span>(<span class="built_in">cin</span>);</span><br><span class="line"><span class="type">int</span> socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>);</span><br><span class="line"><span class="keyword">if</span>(getpeername(accept_fd, (<span class="keyword">struct</span> sockaddr *)&amp;<span class="built_in">cin</span>, &amp;addrlen) &lt; <span class="number">0</span>)</span><br><span class="line">&#123;</span><br><span class="line">	perror(<span class="string">&quot;[error]getsockname&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">if</span> (!inet_ntop(AF_INET, (<span class="type">void</span> *)&amp;<span class="built_in">cin</span>.sin_addr, ipv4_addr, <span class="keyword">sizeof</span>(<span class="built_in">cin</span>)))</span><br><span class="line">&#123;</span><br><span class="line">	perror(<span class="string">&quot;[error]inet_ntop&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">&#125;</span><br><span class="line">port = ntohs(<span class="built_in">cin</span>.sin_port);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong><code>none</code></p>
<h3 id="4-2-使用实例"><a href="#4-2-使用实例" class="headerlink" title="4.2 使用实例"></a><font size=3>4.2 使用实例</font></h3><p>暂无</p>
<h1 id="二、网络超时检测"><a href="#二、网络超时检测" class="headerlink" title="二、网络超时检测"></a><font size=3>二、网络超时检测</font></h1><h2 id="1-为什么要超时检测？"><a href="#1-为什么要超时检测？" class="headerlink" title="1. 为什么要超时检测？"></a><font size=3>1. 为什么要超时检测？</font></h2><p>在网络通信中，很多操作会使得进程阻塞，比如前边<code>TCP</code>套接字中的<code>accept()/connect()/recv()</code>，<code>UDP</code>套接字中的<code>recvfrom()</code>等，进程不能无限制阻塞吧，所以我们就需要进行超时检测，进行超时检测的必要性如下：</p>
<ul>
<li><p>避免进程在没有数据时无限制地阻塞。</p>
</li>
<li><p>当设定的时间到时，进程从原操作返回继续运行。</p>
</li>
</ul>
<h2 id="2-socket属性设置超时"><a href="#2-socket属性设置超时" class="headerlink" title="2. socket属性设置超时"></a><font size=3>2. <code>socket</code>属性设置超时</font></h2><h3 id="2-1-选项与结构体"><a href="#2-1-选项与结构体" class="headerlink" title="2.1 选项与结构体"></a><font size=3>2.1 选项与结构体</font></h3><p>我们上边学习了<code>socket</code>选项的获取和设置，在里边我们可以设置超时时间，此时相关的选项如下：</p>
<table>
    <tr><td align="center">选项名称</td><td align="center">说明</td><td align="center">数据类型</td></tr>
    <tr><td align="left">SO_RCVTIMEO</td><td align="left">接收超时</td><td align="left">struct timeval</td></tr>
    <tr><td align="left">SO_SNDTIMEO</td><td align="left">发送超时</td><td align="left">struct timeval</td></tr>
</table>


<p>其中，<code>struct timeval</code>结构体其实我们前边已经学习过了，我们可以使用<code>man struct timeval</code>命令查看帮助手册，使用该命令后输入以下搜索标记：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">/<span class="class"><span class="keyword">struct</span> <span class="title">timeval</span> &lt;</span>enter&gt;</span><br></pre></td></tr></table></figure>

<p>然后我们便会搜索到该结构体的成员说明：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">timeval</span></span></span><br><span class="line"><span class="class">&#123;</span></span><br><span class="line">	<span class="type">time_t</span>      tv_sec;  <span class="comment">/* Seconds */</span></span><br><span class="line">	<span class="type">suseconds_t</span> tv_usec; <span class="comment">/* Microseconds */</span></span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<h3 id="2-2-使用实例-1"><a href="#2-2-使用实例-1" class="headerlink" title="2.2 使用实例"></a><font size=3>2.2 使用实例</font></h3><h4 id="2-2-1-server服务器端"><a href="#2-2-1-server服务器端" class="headerlink" title="2.2.1 server服务器端"></a><font size=3>2.2.1 <code>server</code>服务器端</font></h4><details class="folding-tag" blue><summary> 点击查看实例 </summary>
              <div class='content'>
              <figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br><span class="line">141</span><br><span class="line">142</span><br><span class="line">143</span><br><span class="line">144</span><br><span class="line">145</span><br><span class="line">146</span><br><span class="line">147</span><br><span class="line">148</span><br><span class="line">149</span><br><span class="line">150</span><br><span class="line">151</span><br><span class="line">152</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/** =====================================================</span></span><br><span class="line"><span class="comment"> * Copyright © hk. 2022-2022. All rights reserved.</span></span><br><span class="line"><span class="comment"> * File name: server.c</span></span><br><span class="line"><span class="comment"> * Author   : fanhua</span></span><br><span class="line"><span class="comment"> * Description: server服务器端——socket超时检测(TCP)</span></span><br><span class="line"><span class="comment"> * ======================================================</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="comment">/* 头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span>      <span class="comment">/* perror */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdlib.h&gt;</span>     <span class="comment">/* exit atoi */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;errno.h&gt;</span>     <span class="comment">/* errno号 */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span>  <span class="comment">/* socket           bind listen accept send */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span> <span class="comment">/* socket inet_addr bind listen accept send */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;strings.h&gt;</span>    <span class="comment">/* bzero */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;arpa/inet.h&gt;</span>  <span class="comment">/* htons  inet_addr inet_pton */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;netinet/in.h&gt;</span> <span class="comment">/* ntohs  inet_addr inet_ntop*/</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span>     <span class="comment">/* close */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;string.h&gt;</span>     <span class="comment">/* strlen strcat*/</span></span></span><br><span class="line"></span><br><span class="line"><span class="type">void</span> <span class="title function_">usage</span><span class="params">(<span class="type">char</span> *str)</span>; <span class="comment">/* 提示信息打印函数 */</span></span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc, <span class="type">char</span> *argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="type">int</span> count = <span class="number">0</span>;</span><br><span class="line">	<span class="comment">/* 1.参数判断及端口号处理 */</span></span><br><span class="line">	<span class="type">int</span> port = <span class="number">-1</span>;</span><br><span class="line">	<span class="keyword">if</span> (argc != <span class="number">3</span>)<span class="comment">/* 参数数量不对时打印提示信息 */</span></span><br><span class="line">	&#123;</span><br><span class="line">		usage(argv[<span class="number">0</span>]);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	port = atoi(argv[<span class="number">2</span>]);<span class="comment">/* 字符串转数字 */</span></span><br><span class="line">	<span class="keyword">if</span> (port &lt; <span class="number">5000</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		usage(argv[<span class="number">0</span>]);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 2.创建套接字，得到socket描述符 */</span></span><br><span class="line">	<span class="type">int</span> socket_fd = <span class="number">-1</span>; <span class="comment">/* 接收服务器端socket描述符 */</span></span><br><span class="line">	<span class="keyword">if</span>((socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>)) &lt; <span class="number">0</span>)<span class="comment">/* SOCK_STREAM,使用TCP协议 */</span></span><br><span class="line">	&#123;</span><br><span class="line">		perror (<span class="string">&quot;socket&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 3.socket属性设置 */</span></span><br><span class="line">	<span class="comment">/* 3.1允许绑定地址快速重用 */</span></span><br><span class="line">	<span class="type">int</span> b_reuse = <span class="number">1</span>;</span><br><span class="line">	setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &amp;b_reuse, <span class="keyword">sizeof</span> (<span class="type">int</span>));</span><br><span class="line">	<span class="comment">/* 3.2 设置超时时间 */</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">timeval</span>  <span class="title">tout</span>;</span></span><br><span class="line">	tout.tv_sec = <span class="number">2</span>;   <span class="comment">/* 设置2秒时间超时 */</span></span><br><span class="line">	tout.tv_usec = <span class="number">0</span>;</span><br><span class="line">	setsockopt(socket_fd, SOL_SOCKET, SO_RCVTIMEO, &amp;tout, <span class="keyword">sizeof</span>(tout)); <span class="comment">/* 设置接收超时 */</span></span><br><span class="line"></span><br><span class="line">	<span class="comment">/* 4.将套接字与指定端口号和IP进行绑定 */</span></span><br><span class="line">	<span class="comment">/* 4.1填充struct sockaddr_in结构体变量 */</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">sockaddr_in</span> <span class="title">sin</span>;</span></span><br><span class="line">	bzero (&amp;<span class="built_in">sin</span>, <span class="keyword">sizeof</span> (<span class="built_in">sin</span>));  <span class="comment">/* 将内存块（字符串）的前n个字节清零 */</span></span><br><span class="line">	<span class="built_in">sin</span>.sin_family = AF_INET;    <span class="comment">/* 协议族, IPv4 */</span></span><br><span class="line">	<span class="built_in">sin</span>.sin_port = htons(port);  <span class="comment">/* 网络字节序的端口号 */</span></span><br><span class="line">	<span class="keyword">if</span>(inet_pton(AF_INET, argv[<span class="number">1</span>], (<span class="type">void</span> *)&amp;<span class="built_in">sin</span>.sin_addr) != <span class="number">1</span>)<span class="comment">/* 填充IP地址,INADDR_ANY表示允许监听任意IP,但是它其实是(in_addr_t) 0x00000000 */</span></span><br><span class="line">	&#123;</span><br><span class="line">		perror (<span class="string">&quot;inet_pton&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 4.2绑定 */</span></span><br><span class="line">	<span class="keyword">if</span>(bind(socket_fd, (<span class="keyword">struct</span> sockaddr *)&amp;<span class="built_in">sin</span>, <span class="keyword">sizeof</span>(<span class="built_in">sin</span>)) &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;bind&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/*5.调用listen()把主动套接字变成被动套接字 */</span></span><br><span class="line">	<span class="keyword">if</span> (listen(socket_fd, <span class="number">5</span>) &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;listen&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;Server starting....OK!\n&quot;</span>);</span><br><span class="line">	<span class="comment">/*6.阻塞等待客户端连接请求 */</span></span><br><span class="line">	<span class="type">int</span> newfd = <span class="number">-1</span>;</span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">sockaddr_in</span> <span class="title">cin</span>;</span>          <span class="comment">/* 用于存储成功连接的客户端的IP信息 */</span></span><br><span class="line">	<span class="type">socklen_t</span> addrlen = <span class="keyword">sizeof</span>(<span class="built_in">cin</span>);</span><br><span class="line">	<span class="keyword">if</span> ((newfd = accept(socket_fd, (<span class="keyword">struct</span> sockaddr *)&amp;<span class="built_in">cin</span>, &amp;addrlen)) &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;accept&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 7.打印成功连接的客户端的信息(此处只能打印一个) */</span></span><br><span class="line">	<span class="type">char</span> ipv4_addr[<span class="number">16</span>];</span><br><span class="line">	<span class="keyword">if</span> (!inet_ntop(AF_INET, (<span class="type">void</span> *)&amp;<span class="built_in">cin</span>.sin_addr, ipv4_addr, <span class="keyword">sizeof</span>(<span class="built_in">cin</span>)))</span><br><span class="line">	&#123;</span><br><span class="line">		perror (<span class="string">&quot;inet_ntop&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;Clinet(%s:%d) is connected successfully![newfd=%d]\n&quot;</span>, ipv4_addr, ntohs(<span class="built_in">cin</span>.sin_port), newfd);</span><br><span class="line"></span><br><span class="line">	<span class="comment">/* 8.数据读写 */</span></span><br><span class="line">	<span class="type">int</span> ret = <span class="number">-1</span>;</span><br><span class="line">	<span class="type">char</span> buf[BUFSIZ]; <span class="comment">/* BUFSIZ是在stdio.h中定义的一个宏，值为8192 */</span></span><br><span class="line">	<span class="type">char</span> replay[BUFSIZ];</span><br><span class="line">	<span class="keyword">while</span>(<span class="number">1</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;count=%d\n&quot;</span>, ++count);</span><br><span class="line">		<span class="comment">/* 8.1接收来自客户端的数据 */</span></span><br><span class="line">		bzero(buf, BUFSIZ);</span><br><span class="line">		bzero(replay, BUFSIZ);</span><br><span class="line">		<span class="keyword">do</span>&#123;</span><br><span class="line">			ret = read(newfd, buf, BUFSIZ - <span class="number">1</span>);</span><br><span class="line">		&#125;<span class="keyword">while</span>(ret &lt; <span class="number">0</span> &amp;&amp; EINTR == errno);</span><br><span class="line">		<span class="keyword">if</span>(ret &lt; <span class="number">0</span>)</span><br><span class="line">		&#123;</span><br><span class="line">			perror(<span class="string">&quot;read&quot;</span>);</span><br><span class="line">			<span class="keyword">continue</span>;</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="keyword">if</span>(!ret) <span class="keyword">break</span>; <span class="comment">/* 对方已经关闭 */</span></span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;Receive data: %s&quot;</span>, buf);</span><br><span class="line">		<span class="comment">/* 8.2对客户端做出应答 */</span></span><br><span class="line">		<span class="built_in">strcat</span>(replay, buf);</span><br><span class="line">		ret = send(newfd, replay, <span class="built_in">strlen</span>(replay), <span class="number">0</span>);</span><br><span class="line">		<span class="keyword">if</span>(ret &lt; <span class="number">0</span>)</span><br><span class="line">		&#123;</span><br><span class="line">			perror(<span class="string">&quot;send&quot;</span>);</span><br><span class="line">			<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="comment">/* 8.3判断是否需要退出 */</span></span><br><span class="line">		<span class="keyword">if</span>(!strncasecmp(buf, <span class="string">&quot;quit&quot;</span>, <span class="built_in">strlen</span>(<span class="string">&quot;quit&quot;</span>)))  	<span class="comment">//用户输入了quit字符</span></span><br><span class="line">		&#123;</span><br><span class="line">			<span class="built_in">printf</span> (<span class="string">&quot;Client is exiting!\n&quot;</span>);</span><br><span class="line">			<span class="keyword">break</span>;</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 9.关闭文件描述符 */</span></span><br><span class="line">	close(newfd);</span><br><span class="line">	close(socket_fd);</span><br><span class="line"></span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * @Function: usage</span></span><br><span class="line"><span class="comment"> * @Description: 用户提示信息打印函数</span></span><br><span class="line"><span class="comment"> * @param str : 当前应用程序命令字符串，一般是./app</span></span><br><span class="line"><span class="comment"> * @return  : none</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="type">void</span> <span class="title function_">usage</span><span class="params">(<span class="type">char</span> *str)</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n%s serv_ip serv_port&quot;</span>, str);</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n\t serv_ip: server ip address&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n\t serv_port: server port(&gt;5000)\n\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n\t Attention: The IP address must be the IP address of the local nic or 0.0.0.0 \n\n&quot;</span>);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<h4 id="2-2-2-client客户端"><a href="#2-2-2-client客户端" class="headerlink" title="2.2.2 client客户端"></a><font size=3>2.2.2 <code>client</code>客户端</font></h4><details class="folding-tag" blue><summary> 点击查看实例 </summary>
              <div class='content'>
              <figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/** =====================================================</span></span><br><span class="line"><span class="comment"> * Copyright © hk. 2022-2022. All rights reserved.</span></span><br><span class="line"><span class="comment"> * File name: cilent.c</span></span><br><span class="line"><span class="comment"> * Author   : fanhua</span></span><br><span class="line"><span class="comment"> * Description: client客户端程序——socket超时检测(TCP)</span></span><br><span class="line"><span class="comment"> * ======================================================</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="comment">/* 头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span>     <span class="comment">/* perror fgets */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdlib.h&gt;</span>    <span class="comment">/* exit atoi*/</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;errno.h&gt;</span>     <span class="comment">/* errno号 */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span>    <span class="comment">/* write close */</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span> <span class="comment">/* socket           connect send */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/socket.h&gt;</span><span class="comment">/* socket inet_addr connect send */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;netinet/in.h&gt;</span><span class="comment">/* inet_addr */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;arpa/inet.h&gt;</span> <span class="comment">/* inet_addr inet_pton htonl*/</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;string.h&gt;</span>   <span class="comment">/* bzero strncasecmp strlen */</span></span></span><br><span class="line"></span><br><span class="line"><span class="type">void</span> <span class="title function_">usage</span><span class="params">(<span class="type">char</span> *str)</span>; <span class="comment">/* 提示信息打印函数 */</span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 主函数 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc, <span class="type">char</span> *argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="comment">/* 1.参数判断及端口号处理 */</span></span><br><span class="line">	<span class="type">int</span> port = <span class="number">-1</span>;</span><br><span class="line">	<span class="type">int</span> portClient = <span class="number">-1</span>;</span><br><span class="line">	<span class="keyword">if</span> (argc != <span class="number">4</span>)<span class="comment">/* 参数数量不对时打印提示信息 */</span></span><br><span class="line">	&#123;</span><br><span class="line">		usage(argv[<span class="number">0</span>]);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	port = atoi(argv[<span class="number">2</span>]);<span class="comment">/* 字符串转数字 */</span></span><br><span class="line">	portClient = atoi(argv[<span class="number">3</span>]);</span><br><span class="line">	<span class="keyword">if</span> (port &lt; <span class="number">5000</span> || portClient &lt; <span class="number">5000</span> || (port == portClient))</span><br><span class="line">	&#123;</span><br><span class="line">		usage(argv[<span class="number">0</span>]);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="comment">/* 2.打开套接字，得到套接字描述符 */</span></span><br><span class="line">	<span class="type">int</span> socket_fd = <span class="number">-1</span>; <span class="comment">/* 接收服务器端socket描述符 */</span></span><br><span class="line">	<span class="keyword">if</span> ((socket_fd = socket(AF_INET, SOCK_STREAM, <span class="number">0</span>)) &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror (<span class="string">&quot;socket&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 3.socket属性设置 */</span></span><br><span class="line">	<span class="comment">/* 3.1允许绑定地址快速重用 */</span></span><br><span class="line">	<span class="type">int</span> b_reuse = <span class="number">1</span>;</span><br><span class="line">	setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &amp;b_reuse, <span class="keyword">sizeof</span> (<span class="type">int</span>));</span><br><span class="line">	<span class="comment">/* 4.连接服务器 */</span></span><br><span class="line">	<span class="comment">/* 4.1填充struct sockaddr_in结构体变量 */</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">sockaddr_in</span> <span class="title">sin</span>;</span></span><br><span class="line">	bzero (&amp;<span class="built_in">sin</span>, <span class="keyword">sizeof</span> (<span class="built_in">sin</span>)); <span class="comment">/* 将内存块（字符串）的前n个字节清零 */</span></span><br><span class="line">	<span class="built_in">sin</span>.sin_family = AF_INET;   <span class="comment">/* 协议族 */</span></span><br><span class="line">	<span class="built_in">sin</span>.sin_port = htons(port); <span class="comment">/* 网络字节序的端口号 */</span></span><br><span class="line">	<span class="comment">/* 5.设置客户端发送接收数据的端口 */</span></span><br><span class="line">	<span class="comment">/* 5.1客户端的 argv[1] 需要与系统的IP一致 */</span></span><br><span class="line">	<span class="keyword">if</span>(inet_pton(AF_INET, argv[<span class="number">1</span>], (<span class="type">void</span> *)&amp;<span class="built_in">sin</span>.sin_addr) != <span class="number">1</span>)<span class="comment">/* IP地址 */</span></span><br><span class="line">	&#123;</span><br><span class="line">		perror (<span class="string">&quot;inet_pton&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 5.2绑定固定的IP 和 端口号 */</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">sockaddr_in</span> <span class="title">sinClient</span>;</span></span><br><span class="line">	bzero(&amp;sinClient, <span class="keyword">sizeof</span> (sinClient)); <span class="comment">/* 将内存块（字符串）的前n个字节清零 */</span></span><br><span class="line">	sinClient.sin_family = AF_INET;   <span class="comment">/* 协议族 */</span></span><br><span class="line">	sinClient.sin_port = htons(portClient); <span class="comment">/* 网络字节序的端口号 */</span></span><br><span class="line">	<span class="keyword">if</span>(inet_pton(AF_INET, argv[<span class="number">1</span>], (<span class="type">void</span> *)&amp;sinClient.sin_addr) != <span class="number">1</span>)<span class="comment">/* IP地址 */</span></span><br><span class="line">	&#123;</span><br><span class="line">		perror (<span class="string">&quot;inet_pton&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 5.3绑定 */</span></span><br><span class="line">	<span class="keyword">if</span>(bind(socket_fd, (<span class="keyword">struct</span> sockaddr *)&amp;sinClient, <span class="keyword">sizeof</span>(sinClient)) &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;bind&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="comment">/* 6.连接 */</span></span><br><span class="line">	<span class="keyword">if</span>(connect(socket_fd, (<span class="keyword">struct</span> sockaddr *)&amp;<span class="built_in">sin</span>, <span class="keyword">sizeof</span>(<span class="built_in">sin</span>)) &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;connect&quot;</span>);</span><br><span class="line">		<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;Client staring...OK!\n&quot;</span>);</span><br><span class="line">	<span class="comment">/* 7.数据读写 */</span></span><br><span class="line">	<span class="type">int</span> ret = <span class="number">-1</span>;</span><br><span class="line">	<span class="type">char</span> buf[BUFSIZ]; <span class="comment">/* BUFSIZ是在stdio.h中定义的一个宏，值为8192 */</span></span><br><span class="line">	<span class="type">char</span> replay[BUFSIZ];</span><br><span class="line">	<span class="keyword">while</span> (<span class="number">1</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="comment">/* 7.1发送数据 */</span></span><br><span class="line">		bzero (buf, BUFSIZ);</span><br><span class="line">		bzero (replay, BUFSIZ);</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;&gt;&quot;</span>);</span><br><span class="line">		<span class="keyword">if</span> (fgets(buf, BUFSIZ - <span class="number">1</span>, <span class="built_in">stdin</span>) == <span class="literal">NULL</span>)</span><br><span class="line">		&#123;</span><br><span class="line">			<span class="keyword">continue</span>;</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="keyword">do</span>&#123;</span><br><span class="line">			ret = write(socket_fd, buf, <span class="built_in">strlen</span>(buf));</span><br><span class="line">		&#125;<span class="keyword">while</span> (ret &lt; <span class="number">0</span> &amp;&amp; EINTR == errno);</span><br><span class="line">		<span class="comment">/* 7.2接收服务器的回馈数据 */</span></span><br><span class="line">		ret = recv(socket_fd, replay, BUFSIZ, <span class="number">0</span>);</span><br><span class="line">		<span class="keyword">if</span>(ret &lt; <span class="number">0</span>)</span><br><span class="line">		&#123;</span><br><span class="line">			perror(<span class="string">&quot;recv&quot;</span>);</span><br><span class="line">			<span class="built_in">exit</span>(<span class="number">-1</span>);</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;server replay:%s&quot;</span>, replay);</span><br><span class="line">		<span class="comment">/* 7.3判断是否需要退出 */</span></span><br><span class="line">		<span class="keyword">if</span> (!strncasecmp(buf, <span class="string">&quot;quit&quot;</span>, <span class="built_in">strlen</span> (<span class="string">&quot;quit&quot;</span>)))  	<span class="comment">//用户输入了quit字符</span></span><br><span class="line">		&#123;</span><br><span class="line">			<span class="built_in">printf</span> (<span class="string">&quot;Client is exiting!\n&quot;</span>);</span><br><span class="line">			<span class="keyword">break</span>;</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 8.关闭文件描述符 */</span></span><br><span class="line">	close(socket_fd);</span><br><span class="line"></span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * @Function: usage</span></span><br><span class="line"><span class="comment"> * @Description: 用户提示信息打印函数</span></span><br><span class="line"><span class="comment"> * @param str : 当前应用程序命令字符串，一般是./app</span></span><br><span class="line"><span class="comment"> * @return  : none</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="type">void</span> <span class="title function_">usage</span><span class="params">(<span class="type">char</span> *str)</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n%s serv_ip serv_port&quot;</span>, str);</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n\t serv_ip: server ip address&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n\t serv_port: server port(&gt;5000)\n\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span> (<span class="string">&quot;\n\t client_port: client portClient(&gt;5000 &amp;&amp; !=port )\n\n&quot;</span>);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<h4 id="2-2-3-Makefile"><a href="#2-2-3-Makefile" class="headerlink" title="2.2.3 Makefile"></a><font size=3>2.2.3 <code>Makefile</code></font></h4><p>由于需要生成两个可执行程序，自己输命令有些繁琐，这里使用<code>make</code>来进行。</p>
<details class="folding-tag" blue><summary> 点击查看 Makefile 文件 </summary>
              <div class='content'>
              <figure class="highlight makefile"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">## =====================================================</span></span><br><span class="line"><span class="comment"># Copyright © hk. 2022-2022. All rights reserved.</span></span><br><span class="line"><span class="comment"># File name: Makefile</span></span><br><span class="line"><span class="comment"># Author   : fanhua</span></span><br><span class="line"><span class="comment"># Description: Makefile文件</span></span><br><span class="line"><span class="comment">## ======================================================</span></span><br><span class="line"><span class="comment"># </span></span><br><span class="line">CC = gcc</span><br><span class="line"></span><br><span class="line">DEBUG = -g -O2 -Wall</span><br><span class="line">CFLAGS += <span class="variable">$(DEBUG)</span></span><br><span class="line"></span><br><span class="line"><span class="comment"># 所有.c文件去掉后缀</span></span><br><span class="line">TARGET_LIST = $&#123;patsubst %.c, %, $&#123;wildcard *.c&#125;&#125; </span><br><span class="line">all : <span class="variable">$(TARGET_LIST)</span></span><br><span class="line"></span><br><span class="line">%.o : %.c</span><br><span class="line">	<span class="variable">$(CC)</span> <span class="variable">$(CFLAGS)</span> -c <span class="variable">$&lt;</span> -o <span class="variable">$@</span></span><br><span class="line"></span><br><span class="line"><span class="meta"><span class="keyword">.PHONY</span>: all clean clean_o clean_out</span></span><br><span class="line">clean : clean_o clean_out</span><br><span class="line">	@rm -vf <span class="variable">$(TARGET_LIST)</span> </span><br><span class="line">	</span><br><span class="line">clean_o :</span><br><span class="line">	@rm -vf *.o</span><br><span class="line">	</span><br><span class="line">clean_out :</span><br><span class="line">	@rm -vf *.out</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<h4 id="2-2-4-测试结果"><a href="#2-2-4-测试结果" class="headerlink" title="2.2.4 测试结果"></a><font size=3>2.2.4 测试结果</font></h4><p>我们执行以下命令编译链接程序，生成两个可执行文件：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">make</span><br></pre></td></tr></table></figure>

<p>然后会有如下提示，并生成两个可执行文件吗，分别为服务器端程序<code>server</code>和客户端程序<code>client</code>：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">gcc -g -O2 -Wall    client.c   -o client</span><br><span class="line">gcc -g -O2 -Wall    server.c   -o server</span><br></pre></td></tr></table></figure>

<p>对于服务器端，我们执行以下命令启动服务器进程：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">./server 0.0.0.0 5001 # 允许监听所有网卡IP及端口</span><br></pre></td></tr></table></figure>

<p>对于客户端，我们执行以下命令启动客户端进程：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">./client 192.168.10.101 5001 5003 # 连接到本地一块网卡的IP，并设置客户端向外发送数据的端口为5003</span><br></pre></td></tr></table></figure>

<p>然后我们就会看到如下现象：</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV06-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B/LV06-03-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B-09-%E7%BD%91%E7%BB%9C%E5%B1%9E%E6%80%A7/img/image-20220705141116835.png" alt="image-20220705141116835" style="zoom:50%;" />

<p>由于我们设置了<code>2s</code>超时，所以在<code>2s</code>内客户端没有连接的话，<code>accept()</code>就会返回，并且显示错误信息，当我们<code>2s</code>内连接客户端后，没有数据从客户端发送到服务器时，每<code>2s</code>就会超时一次，而原本会一直阻塞在<code>recv()</code>函数。设置了超时时候，依然可以正常接收数据。</p>
<h2 id="3-使用函数自身参数"><a href="#3-使用函数自身参数" class="headerlink" title="3. 使用函数自身参数"></a><font size=3>3. 使用函数自身参数</font></h2><p>一般来说，我们一般会使用<code>select()</code>、<code>poll()</code>或者<code>epoll_wait()</code>来查询某个<code>socket</code>文件描述符是否可读或者可写，而这函数一般是带有超时时间的，前边介绍这些函数的时候也有过说明，例如：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">int</span> <span class="title function_">select</span><span class="params">(<span class="type">int</span> nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, <span class="keyword">struct</span> timeval *timeout)</span>;</span><br><span class="line"><span class="type">int</span> <span class="title function_">poll</span><span class="params">(<span class="keyword">struct</span> pollfd *fds, <span class="type">nfds_t</span> nfds, <span class="type">int</span> timeout)</span>;</span><br><span class="line"><span class="type">int</span> <span class="title function_">epoll_wait</span><span class="params">(<span class="type">int</span> epfd, <span class="keyword">struct</span> epoll_event *events, <span class="type">int</span> maxevents, <span class="type">int</span> timeout)</span>;</span><br></pre></td></tr></table></figure>

<h2 id="4-定时器中接收"><a href="#4-定时器中接收" class="headerlink" title="4. 定时器中接收"></a><font size=3>4. 定时器中接收</font></h2><p>还有一种方式就是在定时器中接收数据，因为定时器定时时间到了之后会产生<code>SIGALRM</code>信号，这样我们便可以自定义信号处理函数来接收数据，防止进程一直阻塞。</p>
<h1 id="三、TCP客户端掉线了？"><a href="#三、TCP客户端掉线了？" class="headerlink" title="三、TCP客户端掉线了？"></a><font size=3>三、<code>TCP</code>客户端掉线了？</font></h1><p>对于面向连接的<code>TCP</code>协议的 <code>socket</code>套接字，在实际应用中通常都要检测对端是否处于连接中，连接端口分两种情况：</p>
<ul>
<li>（1）连接正常关闭，调用<code>close()/shutdown()</code>连接正常关闭，<code>send()</code>与<code>recv()</code>等函数立马返回错误，<code>select()</code>函数返回<code>SOCK_ERR</code>;</li>
<li>（2）连接的对端异常关闭，比如网络断掉、突然断电等。</li>
</ul>
<p>对于第一种情况，正常关闭的，就没啥好说的了，关于第二条，我们如何判断呢？我们了解一个概念吗，就是<strong>心跳检测</strong>，就像心跳一样客户端每隔几秒钟发送一个数据包（心跳包）给服务器，告诉服务器，客户端还在线。如果服务器在规定时间内没有收到客户端发来的心跳包，则认为客户端已经掉线。</p>
<h2 id="1-客户端异常掉线的判断"><a href="#1-客户端异常掉线的判断" class="headerlink" title="1. 客户端异常掉线的判断"></a><font size=3>1. 客户端异常掉线的判断</font></h2><h3 id="1-1-应用层自定义心跳包程序"><a href="#1-1-应用层自定义心跳包程序" class="headerlink" title="1.1 应用层自定义心跳包程序"></a><font size=3>1.1 应用层自定义心跳包程序</font></h3><p>自己编写心跳包程序，就是自己的程序加入一条线程，定时向对端发送数据包，查看是否有<code>ACK</code>应答数据包发回，根据<code>ACK</code>的返回情况来管理连接，如果在一定时间内没有收到对方的回应，即认为对方已经掉线。。此方法比较通用，一般使用业务层心跳处理，灵活可控，但会改变现有的协议。</p>
<h3 id="1-2-TCP中使用SO-KEEPALIVE套接字选项"><a href="#1-2-TCP中使用SO-KEEPALIVE套接字选项" class="headerlink" title="1.2 TCP中使用SO_KEEPALIVE套接字选项"></a><font size=3>1.2 <code>TCP</code>中使用<code>SO_KEEPALIVE</code>套接字选项</font></h3><p>使用<code>TCP</code>的<code>keepalive</code>机制，其实在<code>UNIX</code>网络编程不推荐使用<code>SO_KEEPALIVE</code>来做心跳检测。<code>keepalive</code>基本原理如下：</p>
<p><code>TCP</code>内嵌有心跳包，以服务端为例，当<code>server</code>检测到超过一定时间<code>tcp_keepalive_time</code>，一般在<code>linux</code>中是<code>7200s</code>，也就是<code>2h</code>，我们使用以下命令可以查该时间：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">cat /proc/sys/net/ipv4/tcp_keepalive_time</span><br></pre></td></tr></table></figure>

<p>当没有数据传输的时候，会向<code>client</code>客户端发送一个<code>keepalive packet</code>，此时<code>client</code>端一般会有三种反应：</p>
<ul>
<li>（1）<code>client</code>客户端连接正常，返回一个<code>ACK</code>。<code>server</code>端收到<code>ACK</code>后重置计时器,在<code>2</code>小时后再发送探测。如果<code>2</code>小时内连接上有数据传输，那么在该时间的基础上向后推延<code>2</code>小时发送探测包;</li>
<li>（2）<code>client</code>客户端异常关闭，或网络断开。<code>client</code>无响应，<code>server</code>收不到<code>ACK</code>，在一定时间<code>tcp_keepalive_intvl</code>（一般默认是<code>75s</code>）后重发<code>keepalive packet</code>，并且重发一定次数<code>tcp_keepalive_probes</code>（一般默认是<code>9</code>）;</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_"># </span><span class="language-bash">查看 tcp_keepalive_intvl</span></span><br><span class="line">cat /proc/sys/net/ipv4/tcp_keepalive_intvl</span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">查看 tcp_keepalive_probes</span></span><br><span class="line">cat /proc/sys/net/ipv4/tcp_keepalive_probes</span><br></pre></td></tr></table></figure>

<ul>
<li>（3）客户端曾异常关闭，但后来已经重启。<code>server</code>收到的探测响应是一个复位，<code>server</code>会端终止连接。</li>
</ul>
<blockquote>
<p>我们还可以使用如下命令查看上边三个值的设置情况：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo sysctl -a | grep keepalive</span><br></pre></td></tr></table></figure>

<p>默认情况下应该会显示如下信息：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">[sudo] hk 的密码： </span><br><span class="line">net.ipv4.tcp_keepalive_intvl = 75</span><br><span class="line">net.ipv4.tcp_keepalive_probes = 9</span><br><span class="line">net.ipv4.tcp_keepalive_time = 7200</span><br></pre></td></tr></table></figure>


</blockquote>
<p>【注意事项】</p>
<p>（1）根据 <code>MSDN</code> 的文档，如果为 <code>socket</code> 设置了<code>KEEPALIVE</code>选项，<code>TCP/IP</code> 栈在检测到对方掉线后, 任何在该 <code>socket </code>上进行的调用(发送&#x2F;接受调用)就会立刻返回，错误号是 <code>WSAENETRESET</code> ；同时，此后的任何在该<code>socket</code>句柄的调用会立刻失败，并返回<code>WSAENOTCONN</code>错误。</p>
<p>（2）<code>SO_KEEPALIVE</code>设置空闲<code>2</code>小时才发送一个“保持存活探测分节”，不能保证实时检测。对于判断网络断开时间太长，对于需要及时响应的程序不太适应。当然也可以修改时间间隔参数，但是会影响到所有打开此选项的套接口，关联完成端口的<code>socket</code>可能会忽略掉该套接字选项。</p>
<h3 id="1-3-内核检测"><a href="#1-3-内核检测" class="headerlink" title="1.3 内核检测"></a><font size=3>1.3 内核检测</font></h3><ul>
<li><p>在 <code>2.6</code>内核里面的网卡驱动中，使能<code>1s</code>的周期性检查定时器</p>
</li>
<li><p>网卡硬件或者我们通过<code>GPIO</code>，插拔网线时候产生中断，处理相应中断，这样的话可以立即检测到。</p>
</li>
</ul>
<h2 id="2-SO-KEEPALIVE的使用"><a href="#2-SO-KEEPALIVE的使用" class="headerlink" title="2. SO_KEEPALIVE的使用"></a><font size=3>2. <code>SO_KEEPALIVE</code>的使用</font></h2><p>一般来说，我们可以通过设置网络属性来使用<code>SO_KEEPALIVE</code>参数完成“心跳检测”：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 主函数中应有的部分 */</span></span><br><span class="line"><span class="type">int</span> keepAlive = <span class="number">1</span>;			<span class="comment">/* 设定KeepAlive */</span></span><br><span class="line"><span class="type">int</span> keepIdle = <span class="number">5</span>;			<span class="comment">/* 开始首次KeepAlive探测前的TCP空闭时间 */</span></span><br><span class="line"><span class="type">int</span> keepInterval = <span class="number">5</span>;		<span class="comment">/* 两次KeepAlive探测间的时间间隔 */</span></span><br><span class="line"><span class="type">int</span> keepCount = <span class="number">3</span>;			<span class="comment">/* 判定断开前的KeepAlive探测次数 */</span></span><br><span class="line">setKeepAlive(socket_fd, keepAlive, keepIdle, keepInterval, keepCount); <span class="comment">/* 设置参数 */</span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 自定义函数 */</span></span><br><span class="line"><span class="type">void</span> <span class="title function_">setKeepAlive</span><span class="params">(<span class="type">int</span> socket_fd, <span class="type">int</span> attr_on, <span class="type">socklen_t</span> idle_time, <span class="type">socklen_t</span> interval, <span class="type">socklen_t</span> cnt)</span></span><br><span class="line">&#123;</span><br><span class="line">	setsockopt(socket_fd, SOL_SOCKET, SO_KEEPALIVE, (<span class="type">const</span> <span class="type">char</span> *) &amp;attr_on, <span class="keyword">sizeof</span>(attr_on));</span><br><span class="line">	setsockopt(socket_fd, SOL_TCP, TCP_KEEPIDLE, (<span class="type">const</span> <span class="type">char</span> *) &amp;idle_time, <span class="keyword">sizeof</span>(idle_time));</span><br><span class="line">	setsockopt(socket_fd, SOL_TCP, TCP_KEEPINTVL, (<span class="type">const</span> <span class="type">char</span> *) &amp;interval, <span class="keyword">sizeof</span>(interval));</span><br><span class="line">	setsockopt(socket_fd, SOL_TCP, TCP_KEEPCNT, (<span class="type">const</span> <span class="type">char</span> *) &amp;cnt, <span class="keyword">sizeof</span>(cnt));</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>


    </div>

    
    
    

    <footer class="post-footer">




    <div>
        
            <div style="text-align:center;color: #ccc;font-size:14px;">
            ----------本文结束
            <i class="fas fa-fan fa-spin" style="color: #FF1493; font-size: 1rem"></i>
            感谢您的阅读----------
            </div>
        
    </div>





  
  <div class="my_post_copyright"> 
    <p><span>文章标题:</span><a href="/post/67b61f6b.html">LV06-03-网络编程-09-网络属性</a></p>
    <p><span>文章作者:</span><a href="/" title="欢迎访问 《苏木》 的学习笔记">苏木</a></p>
    <p><span>发布时间:</span>2024年10月27日 - 11:50</p>
    <p><span>最后更新:</span>2025年06月14日 - 00:25</p>
    <p><span>原始链接:</span><a href="/post/67b61f6b.html" title="LV06-03-网络编程-09-网络属性">https://sumumm.github.io/post/67b61f6b.html</a></p>
    <p><span>许可协议:</span><i class="fab fa-creative-commons"></i> <a rel="license" href= "https://creativecommons.org/licenses/by-nc-nd/4.0/" target="_blank" title="Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)">署名-非商业性使用-禁止演绎 4.0 国际</a> 转载请保留原文链接及作者。</p>  
  </div>
  


          <div class="post-tags">
              <a href="/tags/LV06-%E7%BD%91%E7%BB%9C%E7%BC%96%E7%A8%8B/" rel="tag"><i class="fa fa-tag"></i> LV06-网络编程</a>
          </div>

        

          <div class="post-nav">
            <div class="post-nav-item">
                <a href="/post/5a896934.html" rel="prev" title="LV06-03-网络编程-10-广播与多播">
                  <i class="fa fa-angle-left"></i> LV06-03-网络编程-10-广播与多播
                </a>
            </div>
            <div class="post-nav-item">
                <a href="/post/a07b6c8b.html" rel="next" title="LV06-03-网络编程-08-域名解析">
                  LV06-03-网络编程-08-域名解析 <i class="fa fa-angle-right"></i>
                </a>
            </div>
          </div>
    </footer>
  </article>
</div>






</div>
  </main>

  <footer class="footer">
    <div class="footer-inner">

  <div class="copyright">
    &copy; 2017 – 
    <span itemprop="copyrightYear">2025</span>
    <span class="with-love">
      <i class="fa fa-heart"></i>
    </span>
    <span class="author" itemprop="copyrightHolder">苏木</span>
  </div>
<div class="wordcount">
  <span class="post-meta-item">
    <span class="post-meta-item-icon">
      <i class="fa fa-chart-line"></i>
    </span>
      <span>站点总字数：</span>
    <span title="站点总字数">3.7m</span>
  </span>
  <span class="post-meta-item">
    <span class="post-meta-item-icon">
      <i class="fa fa-coffee"></i>
    </span>
      <span>站点阅读时长 &asymp;</span>
    <span title="站点阅读时长">225:26</span>
  </span>
</div>




    <span id="sitetime"></span>
    <script defer language=javascript>
        function siteTime()
        {
            window.setTimeout("siteTime()", 1000);
            var seconds = 1000;
            var minutes = seconds * 60;
            var hours = minutes * 60;
            var days = hours * 24;
            var years = days * 365;
            var today = new Date();
            var todayYear = today.getFullYear();
            var todayMonth = today.getMonth()+1;
            var todayDate = today.getDate();
            var todayHour = today.getHours();
            var todayMinute = today.getMinutes();
            var todaySecond = today.getSeconds();
            /*==================================================
            Date.UTC() -- 返回date对象距世界标准时间(UTC)1970年1月1日午夜之间的毫秒数(时间戳)
            year        - 作为date对象的年份，为4位年份值
            month       - 0-11之间的整数，做为date对象的月份
            day         - 1-31之间的整数，做为date对象的天数
            hours       - 0(午夜24点)-23之间的整数，做为date对象的小时数
            minutes     - 0-59之间的整数，做为date对象的分钟数
            seconds     - 0-59之间的整数，做为date对象的秒数
            microseconds - 0-999之间的整数，做为date对象的毫秒数
            ==================================================*/
            var t1 = Date.UTC(2017, 
                              5, 
                              19, 
                              0, 
                              0, 
                              0); //北京时间
            var t2 = Date.UTC(todayYear,todayMonth,todayDate,todayHour,todayMinute,todaySecond);
            var diff = t2-t1;
            var diffYears = Math.floor(diff/years);
            var diffDays = Math.floor((diff/days)-diffYears*365);
            var diffHours = Math.floor((diff-(diffYears*365+diffDays)*days)/hours);
            var diffMinutes = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours)/minutes);
            var diffSeconds = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours-diffMinutes*minutes)/seconds);
            document.getElementById("sitetime").innerHTML="已在这里 "+diffYears+" 年 "+diffDays+" 天 "+diffHours+" 小时 "+diffMinutes+" 分钟 "+diffSeconds+" 秒";
        }
        siteTime();
    </script>



    </div>
  </footer>

  
  <div class="back-to-top" role="button" aria-label="返回顶部">
    <i class="fa fa-arrow-up fa-lg"></i>
    <span>0%</span>
  </div>
  <div class="reading-progress-bar"></div>

<noscript>
  <div class="noscript-warning">Theme NexT works best with JavaScript enabled</div>
</noscript>


  
  <script src="https://cdnjs.cloudflare.com/ajax/libs/animejs/3.2.1/anime.min.js" integrity="sha256-XL2inqUJaslATFnHdJOi9GfQ60on8Wx1C2H8DYiN1xY=" crossorigin="anonymous"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/next-theme-pjax/0.6.0/pjax.min.js" integrity="sha256-vxLn1tSKWD4dqbMRyv940UYw4sXgMtYcK6reefzZrao=" crossorigin="anonymous"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/fancyapps-ui/5.0.28/fancybox/fancybox.umd.js" integrity="sha256-ytMJGN3toR+a84u7g7NuHm91VIR06Q41kMWDr2pq7Zo=" crossorigin="anonymous"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/lozad.js/1.16.0/lozad.min.js" integrity="sha256-mOFREFhqmHeQbXpK2lp4nA3qooVgACfh88fpJftLBbc=" crossorigin="anonymous"></script>
<script src="/js/comments.js"></script><script src="/js/utils.js"></script><script src="/js/motion.js"></script><script src="/js/next-boot.js"></script><script src="/js/pjax.js"></script>

  <script src="https://cdnjs.cloudflare.com/ajax/libs/hexo-generator-searchdb/1.4.1/search.js" integrity="sha256-1kfA5uHPf65M5cphT2dvymhkuyHPQp5A53EGZOnOLmc=" crossorigin="anonymous"></script>
<script src="/js/third-party/search/local-search.js"></script>




  <script src="/js/third-party/fancybox.js"></script>

  <script src="/js/third-party/pace.js"></script>


  




  

  <script class="next-config" data-name="enableMath" type="application/json">true</script><script class="next-config" data-name="mathjax" type="application/json">{"enable":true,"tags":"none","js":{"url":"https://cdnjs.cloudflare.com/ajax/libs/mathjax/3.2.2/es5/tex-mml-chtml.js","integrity":"sha256-MASABpB4tYktI2Oitl4t+78w/lyA+D7b/s9GEP0JOGI="}}</script>
<script src="/js/third-party/math/mathjax.js"></script>


 
        <div id="click-show-text"
            data-mobile = false
            data-text = 富强,民主,文明,和谐,自由,平等,公正,法制,爱国,敬业,诚信,友善
            data-fontsize = 15px
            data-random= false>
        </div>
       

      
        <script async src=https://cdn.jsdelivr.net/npm/hexo-next-mouse-effect@latest/click/showText.js></script>
      

      
    




    <script async src="/js/fancybox_param.js"></script>





<!-- APlayer本体 -->



</body>
</html>
